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A A Yousten

Publications and source records attributed to A A Yousten.

At least 19 recordsLinked to original sources
PubMed1995

Random amplified polymorphic DNA fingerprinting of mosquito-pathogenic and nonpathogenic strains of Bacillus sphaericus.

Random amplified polymorphic DNA fingerprinting was used to examine 31 mosquito-pathogenic and 14 nonpathogenic strains of Bacillus sphaericus. We verified that DNA bands that migrated the same distance in an agarose gel were homologous by using PCR-generated probes made from the random amplified polymorphic DNA bands. The band patterns obtained with eight primers were analyzed by using the Jaccard coefficient and unweighted pair group with arithmetic average clustering. Pathogenic strains belonging to DNA homology group IIA were similar to strains belonging to nonpathogenic homology groups at an average level of similarity of 6.3%. Individual serotypes were clearly identified among the pathogenic strains. This suggests that there is overall genetic homogeneity among strains within serotypes. It is also consistent with the uniform toxicity pattern found for each serotype (unlike the toxin diversity found in Bacillus thuringiensis serotypes). These results, together with DNA homology data, support the proposal that a new species should be described for the pathogenic strains.

Animals↗
PubMed1992

Fate of Bacillus sphaericus and Bacillus thuringiensis serovar israelensis in the aquatic environment.

Bacillus sphaericus spores were suspended in bottles of filtered (0.45 microns) freshwater and seawater under various conditions of temperature, pH and salinity. Heat resistant culturable counts (spores) slowly decreased with time. Spores suspended in dialysis bags submerged in a freshwater pond or in flowing seawater underwent a more rapid drop in heat resistant spore counts than did spores held in bottles. Thus, laboratory studies may overestimate spore longevity in the environment. Spore settling rate was related to the nature of particulate material in the water column. Paraspores (or perhaps spores and toxin) of B. thuringiensis serovar israelensis (B.t.i.) had a greater tendency to adhere to and settle with suspended sediment and fine particulates than did paraspores of B. sphaericus. These observations may at least partially explain the greater persistence of B. sphaericus larvicidal activity in field tests than that of B.t.i..

Animals↗
PubMed1991

Plasmid stability in Bacillus sphaericus 2362 during recycling in mosquito larvae.

Bacillus sphaericus 2362 strains transformed with the plasmid pUB110 (4.5 kb) and plasmids derived from it, pLDT103 (7.6 kb) and pLDT117 (9.3 kb), were able to recycle (spore germination, vegetative growth, sporulation) in larvae of Culex quinquefasciatus. During the course of recycling, the pUB110 vector and the recombinant plasmid pLDT103 were stable (100 and 99.2%, respectively). However, the recombinant plasmid pLDT117 exhibited 23% segregational instability. Isolates which lost pLDT117 during recycling retained the one large plasmid native to B. sphaericus 2362.

Animals↗
PubMed1991

Fate of Bacillus sphaericus 2362 spores following ingestion by nontarget invertebrates.

Elimination of Bacillus sphaericus spores ingested by midge larvae, snails, and oysters was most rapid among midge larvae. Spores remained in oysters up to 21 days and in snails up to 49 days. Viable spores were recovered in snail and oyster feces for these same periods. There was no indication of actively growing B. sphaericus in the animals. Passage through oyster gut detoxified the B. sphaericus mosquito larval toxin, but there was a 33% retention of toxicity following snail gut passage. Midge larvae reared to adults in spore-containing water carried spores in/on the adult body. This suggests that these animals could carry the bacteria to sites beyond the application area.

Animals↗
PubMed1989

Thuricin: the bacteriocin produced by Bacillus thuringiensis.

Bacillus thuringiensis serovar, thuringiensis (HD-2) demonstrated antibacterial activity against 48 of 56 strains of B. thuringiensis and against some other Gram-positive species but not against Gram-negative species. The antibacterial activity was not inducible by mitomycin C or by ultraviolet irradiation, and additional activity was not liberated from cells by sonication. Upon dilution of the antibacterial substance, zones of inhibition diminished without the appearance of plaques. Gel filtration chromatography indicated an Mr greater than 950,000 for the bacteriocin (thuricin) in its native form. The native thuricin was sedimented by ultracentrifugation, but electron microscopy of the pellet failed to reveal phage particles or phage components. Nondenaturing polyacrylamide gel electrophoresis (PAGE) of thuricin demonstrated the association of bacteriocin activity with a protein band which migrated only slightly into a 5% gel. Sodium dodecyl sulfate (SDS)-PAGE of partially purified thuricin revealed five major bands. Thuricin activity was substantially reduced by treatment with chymotrypsin, pronase, subtilisin, trypsin, and heat at 96 degrees C but not by treatment with lysozyme, phospholipase C, papain, peptidase, or organic solvents. It exhibited a bactericidal and bacteriolytic effect on a sensitive strain, B. thuringiensis serovar, canadensis (MF4). Partially purified preparations of thuricin had phospholipase A activity which was adsorbed by sensitive cells but not by cells which were insensitive to thuricin. Antibacterial activity was blocked by preincubation of thuricin with phospholipid. Loss of a 150-mDa plasmid was correlated with loss of thuricin production.

Animals↗
PubMed1989

Carbohydrate metabolism in the mosquito pathogen Bacillus sphaericus 2362.

Bacillus sphaericus 2362 is pathogenic for mosquito larvae and is being considered for large-scale production as a larvicide. The inability of the bacteria to metabolize carbohydrates requires that they be grown on proteinaceous media. This bacterium was found to be unable to transport glucose or sucrose into the cell, and it lacked glucokinase and hexokinase activity. In addition, it lacked phosphoglucose isomerase, phosphofructokinase, and glucose 6-phosphate dehydrogenase, which are early enzymes of the Embden-Myerhof-Parnas and hexose monophosphate pathways. The presence of other enzymes in these pathways was indicated by assay, by the metabolism of glycerol to acetate, and by growth on acetate and gluconate as sole carbon sources. Critical enzymes of the Entner-Doudoroff pathway were also shown to be absent.

Animals↗
PubMed1989

Cloning and sequencing of the gene encoding a 125-kilodalton surface-layer protein from Bacillus sphaericus 2362 and of a related cryptic gene.

Using the vector pGEM-4-blue, a 4,251-base-pair DNA fragment containing the gene for the surface (S)-layer protein of Bacillus sphaericus 2362 was cloned into Escherichia coli. Determination of the nucleotide sequence indicated an open reading frame (ORF) coding for a protein of 1,176 amino acids with a molecular size of 125 kilodaltons (kDa). A protein of this size which reacted with antibody to the 122-kDa S-layer protein of B. sphaericus was detected in cells of E. coli containing the recombinant plasmid. Analysis of the deduced amino acid sequence indicated a highly hydrophobic N-terminal region which had the characteristics of a leader peptide. The first amino acid of the N-terminal sequence of the 122-kDa S-layer protein followed the predicted cleavage site of the leader peptide in the 125-kDa protein. A sequence characteristic of promoters expressed during vegetative growth was found within a 177-base-pair region upstream from the ORF coding for the 125-kDa protein. This putative promoter may account for the expression of this gene during the vegetative growth of B. sphaericus and E. coli. The gene for the 125-kDa protein was followed by an inverted repeat characteristic of terminators. Downstream from this gene (11.2 kilobases) was an ORF coding for a putative 80-kDa protein having a high sequence similarity to the 125-kDa protein. Evidence was presented indicating that this gene is cryptic.

Amino Acid Sequence↗
PubMed1987

Characterization of the surface protein layers of the mosquito-pathogenic strains of Bacillus sphaericus.

The protein surface layers on the cell walls of mosquito-pathogenic and nonpathogenic Bacillus sphaericus strains were studied by structural, biochemical, and serological methods. The surface structure of two representative insect-pathogenic strains had the form of a delicate linear array with a repeat interval of 5 nm. This was distinctly different from the tetragonal array of the P-1 strain in spacing and arrangement. The surface layers were composed of acidic glycoproteins with molecular weights ranging from approximately 133,000 to 155,000. Peptide mapping and serological analysis of the surface proteins revealed eight distinct groups among the pathogens. These groups were very similar to the groupings determined by flagellar-antigen serotyping and bacteriophage typing.

Amino Acid Sequence↗
PubMed1980

Localization of a mosquito-larval toxin of Bacillus sphaericus 1593.

Cell-free wall, membrane, and cytoplasmic fractions were prepared from Bacillus sphaericus 1593, which exhibited toxic activity against larvae of the mosquito Culex pipiens var. quinquefasciatus. Breakage of 12- to 14-h cells by sonication or French pressure cell yielded toxic material which could be assayed in a standard mosquito larva bioassay. When sporulating cells of strain 1593 were fractionated, the majority of the toxic activity was localized in the cell wall rather than in the plasma membrane or cytoplasm. The toxin located in the bacterial cell wall was relatively stable, in that activity was unaffected by treatment with trypsin, pronase, CHCl3-CH3OH-water, Triton X-100, 8 M urea (30 min), heat (80 degrees C, 12 min), sonication, refrigeration, lyophilization, or freezing. Activity was destroyed by boiling for 10 min or by 0.01 N NaOH. Only about 1.0% of the activity present in purified cell walls could be recovered by a 2-h extraction with 8 M urea or 3 M guanidine hydrochloride. A comparison of the toxicity of a cell-free cell wall fraction with that of a sample consisting entirely of heat-stable spores indicated that the spore preparation was about 10 times more active.

Animals↗
PubMed1979

Comparative studies of the mosquito-larval toxin of Bacillus sphaericus SSII-1 and 1593.

Two strains of Bacillus sphaericus. SSII-1 and 1593, were bioassayed for toxic activity against second-instar larvae of the mosquito Culex pipiens quinquefasciatus. It was found that strain 1593 developed a level of toxicity 3000 times that of strain SSII-1. Although the toxic activity of B. sphaericus SSII-1 was relatively unchanged throughout growth, an increase in activity of strain 1593 occurred as the bacteria began to sporulate. Strain differences were examined by (i) growth cycle experiments, (ii) bioassays of the toxicity of oligosporogenous mutants, and (iii) manganese limitation experiments. The toxin of strain 1593 was shown to be more stable than that of strain SSII-1. Unlike the spores of strain SSII-1, the spores of B. sphaericus 1593 were found to be highly toxic. Thin sections of SSII-1 or 1593 cells did not reveal the presence of any inclusion body that might be related to toxicity.

Animals↗
PubMed1978

Toxic activity of Bacillus sphaericus SSII-1 for mosquito larvae.

Using larvae of the mosquito Culex pipiens var. quinquefasciatus as a bioassay system, we have verified an earlier proposal that pathogenicity of Bacillus sphaericus SSII-1 is a toxin-mediated rather than an infectious process. Chloroform or ultraviolet-light treatments that decreased the viable count of SSII-1 cells by 4 or 5 logs did not significantly alter the ability of the bacterial cells to kill larvae. Three lines of evidence indicated that toxic activity was not related to sporulation: (i) cells grown in either a complex or a defined medium were toxic at all ages; (ii) when supplemental Mn2+ was excluded from a complex medium, the culture yielded few spores but was of equal toxicity to a culture containing many spores; and (iii) several early blocked oligosporogenous mutants were isolated that had toxic activities comparable to that of the parent. The toxin was shown to be relatively unstable because activity was destroyed by heat and decreased by refrigeration, a freeze-thaw cycle, or two methods of cell breakage. Thin sections of SSII-1 cells did not reveal the presence of any inclusion body that might be related to toxicity.

Animals↗
PubMed1976

Response of Bacillus thuringiensis to bacteriophage CP-51.

Bacteriophage CP-51, a transducing phage of Bacillus cereus was able to replicate on all eight varieties of Bacillus thuringiensis tested. Three general plaque types were observed on each strain although one type predominated on each strain. The plaque size was uniform for each strain regardless of plaque type. The bacterial strain used as source of the phage had no effect on plaque type or size found on any host strain. CP-51 was stable in infected spores of B. thuringiensis var. kurstaki for at least 305 days even though most of the spores had lost refractility. Free phage paricles produced in B. thuringiensis were stable for at least 10 days in broth at 14 degrees C but were very unstable at 4 degrees C.

Bacillus cereus↗